What is Kratom’s Half Life? | Kratom Monkey

“What is the half-life of mitragynine?” is a better question to ask. This indole-based alkaloid is the most vital active compound in kratom. Studies suggest that mitragynine has a plasma elimination half-life of four hours and a terminal half-life of 23 hours.

However, other studies have produced different findings, meaning the precise half-lives of these substances is still up for debate. In this article, I will look in-depth at the half-life of mitragynine before discussing what it all means regarding drug tests.

Ready? Let’s do it. 

A drug’s half-life is the time it takes for the active concentration of a substance in your system to reduce by 50%. The half-life statistic is drug-dependent, with some drugs exiting the body in minutes and others lingering for days.

The half-life of a substance is affected by its pharmacokinetics (i.e., how the body absorbs, distributes, metabolizes, and eliminates it). Drugs work via different mechanisms, hence why each substance has a distinct half-life.

However, even though the half-life of a drug is described with precision, it is still only an estimate. Factors like age, metabolism speed, and liver health can all affect a drug’s half-life. For example, a young, healthy person can eliminate a drug faster than an older person with liver issues.

Even in 2023, scientific research on kratom remains thin on the ground. The herb’s popularity soared in the mid-2010s but was niche and unknown by the wider world until then.

Therefore, relative to other substances, we are still discovering the basics of kratom and its compounds. Even the half-life of prominent alkaloids like mitragynine is not a settled matter. But let’s examine what we know from the available research.

In 2009, the Journal of Chromatography B published a study analyzing mitragynine’s half-life in rat plasma.

Rodent research often - albeit not always - provides an indication of what to expect in humans. This study found that mitragynine has an elimination half-life of 3.85 hours, plus or minus 0.52 hours.

In 2015, the Drug Design, Development and Therapy journal published a paper titled, “The Pharmacokinetics of Mitragynine in Man.”

This first-of-its-kind study involved giving kratom tea to 10 regular kratom users for seven days and exploring various pharmacokinetic areas, including mitragynine’s terminal half-life.

But the study’s findings left much to be desired. Mitragynine was determined to have a half-life of 23.24 hours, plus or minus 16.07 hours. So, mitragynine’s half-life could be anywhere between seven and 39 hours - thanks for that, scientists!

To make sense of these numbers, you must understand that there are two types of drug half-life: the plasma elimination half-life and the terminal half-life.

The first statistic describes how long it takes for the active amount of a substance to reduce by half. The second refers to how long it takes for half of a substance to be entirely removed from the body.

The rat study focused on mitragynine’s plasma elimination half-life, while the human study examined the alkaloid’s terminal half-life. This explains the substantial differences in the findings.

Now you know more about mitragynine half-life, let’s calculate how long the alkaloid remains active in your system and detectable in your body. The mitragynine half-life studies had substantial margins for error, but we will work on the assumption that the figures are accurate.

It takes four or five half-lives to eliminate 94 to 97% of a drug from your system. The substance should no longer be having an effect after that time, although it may still be detectable in tests.

Plasma Elimination Half-Life: Based on a half-life of 3.85 hours, mitragynine’s effects should have worn off between 15 and 19 hours after your dosage.

Terminal Half-Life: Based on a half-life of 23.24 hours, your body will take almost five days to remove up to 97% of a mitragynine dosage. 

Kratom stays in people's bodies for different durations. This is due to several factors, including kratom product strength, regularity of use, and biological variables. Let's delve deeper into each.

Kratom products with high concentrations of mitragynine and 7-hydroxymitragynine (7-HMG) take longer to clear from your system than products with lower amounts.

For example, if you take 100mg of mitragynine in one hit, 6.25mg will remain active after four half-lives. But if you took 200mg of mitragynine in one go, it would take five half-lives to reduce the active amount in your system to 6.25mg.

Kratom alkaloids stay in the bodies of regular users for longer than in occasional consumers. If you frequently top up your dosage, you are introducing fresh mitragynine into your body before it has cleared the last.

Over time, the active concentration of mitragynine in your system will steadily increase. And as discussed, the more mitragynine in your body, the longer it takes to clear.

The faster your metabolism speed, the quicker your body can eliminate kratom alkaloids from your system. Metabolism speed gradually slows with age, although there is no reason why you cannot maintain a fast metabolism if you keep healthy.

Liver health also affects how efficiently your body metabolizes and eliminates mitragynine and 7-HMG. A compromised liver takes longer to deal with drugs and toxins than a well-functioning one.

Some evidence suggests there is a rare association between kratom use and liver damage. While on this topic, it is worth noting that hydration, exercise, and a well-balanced diet all support good liver health. 

Yes, I know this is what you are getting at with all those questions concerning kratom's half-life and how long the substance remains in your body.

Essentially, there are ways of testing for kratom use. But it's relatively uncommon to do so, and quite rightly! After all, kratom is a legal substance in most of the U.S.

Testing for kratom alkaloids is also tricky and expensive. The most widely-used drug tests are rarely set up to check for these compounds. However, some drug testing companies have begun to offer kratom testing options due to the growing demand.

Urine: This type of screening is still the most common way of testing for substances. However, the standard multi-panel urine dip tests do not typically have a strip for kratom alkaloids. But a specialized urine test could theoretically detect kratom metabolites for several days after use.

Saliva (Oral Fluid): These tests have emerged as a more efficient and less invasive alternative to urine screening. A quick cheek swab is all that is needed to get a sufficient sample. Judging by other substances, kratom alkaloid metabolites likely stay in your saliva for a few days.

Blood: This type of test is good at detecting current substance use. You may be asked to take a blood test if involved in an accident at work or suspected of driving under the influence. Blood tests can identify whether kratom alkaloid metabolites are in your system.

Hair Follicle: Drug metabolites hang around in your hair for many weeks. Hence, hair follicle tests are excellent at detecting historic substance use. I have not seen any examples of these tests being used to check for kratom, but it is technically possible. 

There are situations where they might. But employers testing for kratom use is most unusual and only happens in specific scenarios.

For example, employees in Indiana may be more likely to get drug tested for kratom since the herb is illegal in the state. However, even then, the employer would need to cough up the cash to carry out such testing. And the cost-benefit analysis might not be worth it.

Active military service members should be more cautious about kratom drug tests than civilians. While kratom is federally legal, the Department of Defense bans it among military personnel.

False positive drug tests are a concern with kratom products - and there are two ways these could manifest. Cheap tests may mistake kratom alkaloids for opioids. Alternatively, and more worryingly, your kratom product could be adulterated with illicit substances.

With low-quality tests, you can request that your sample be sent to a laboratory for extensive analysis. This will conclusively prove that you did not have a banned substance in your system.

However, testing positive due to an adulterated kratom product would not strictly be a false positive. Even though you had no knowledge, such a test result would be accurate. In this event, you may struggle to prove your innocence to your employer.

Kratom’s half-life is a complex topic, but I hope this article cleared things up! We still need more studies to confirm the statistics on mitragynine’s half-life. With kratom becoming more mainstream by the year, I expect we will learn more about the substance soon.